Flexible lance drive apparatus with autostroke function

ABSTRACT

An apparatus for sensing an obstruction within a tube being cleaned and repetitively advancing and retracting a flexible high pressure fluid cleaning lance within the tube is disclosed. The apparatus monitors drive roller/belt position and actual hose position, compares the belt (expected travel) to hose position (travel) and generates a position difference, or mismatch. If the mismatch is above a predetermined level, the drive motor direction is reversed for a predetermined time interval, and forward operation restored after the predetermined time interval; and the sequence of repeating the reversing and restoring operations is continued until the position difference or mismatch no longer exceeds the predetermined difference threshold.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalPatent Application Ser. No. 62/751,423, filed Oct. 26, 2018. Thisapplication also is a continuation in part of U.S. patent applicationSer. No. 16/119,586, filed Aug. 31, 2018, which is a divisional of U.S.patent application Ser. No. 15/270,926, filed Sep. 20, 2016, having theabove title, which claims the benefit of priority of U.S. ProvisionalPatent Application No. 62/240,169 filed Oct. 12, 2015, the content ofeach of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE DISCLOSURE

The present disclosure is directed to high pressure fluid rotary nozzlehandling systems. In particular, embodiments of the present disclosureare directed to an apparatus for advancing and retracting one or moreflexible tube cleaning lances from tubes arranged in an array, such asin a heat exchanger, from a position adjacent a heat exchanger tubesheet, and automatically repetitively reversing forward lance feedmovement upon encountering an obstruction within a tube or other pipingsystem being cleaned.

One conventional tube lancing apparatus consists of a rotating reelflexible lance hose take-up and hose dispensing apparatus that carries apredetermined length of flexible lance hose wrapped around a drum. Thereel in the drum is rotated by an air motor to push the flexible lanceout of the drum and into one or two heat exchanger tubes. The air motordrive can be automatically reversed upon pneumatically sensing a largeair pressure increase in air pressure supplied to the forwarddirectional side motor that occurs if the flexible lance being pushed bythe reel rotation encounters an obstruction within a tube being cleaned.In this instance, when such a pressure increase is sensed, an airoperated valve to the air motor drive shuts off air to the forward sideof the air motor and supplies air to the opposite side of the air motor,the air motor reverses, withdrawing the lance for a predeterminedtime/distance. This automatic reversal of the air motor drive can thenbe repeated until the obstruction within the tube is removed. In thismanner, the flexible lance “pecks” at a restriction, or obstruction,within the tube until the undesirable pressure increase is no longersensed (indicating that the obstruction has been removed). This drum andreel apparatus necessarily must be somewhat remotely located from theheat exchanger tube sheet in order to accommodate the size of the drumand air drive motor apparatus.

One problem with this approach is that it takes a substantial increasein air pressure—virtually a stall of the flexible lance within the tube,to cause the pressure to increase sufficiently to trigger reversal.Furthermore, if the flexible lance is far within a tube being cleaned,the length of hose within the tube generates resistance against theforward air motor supply pressure pushing the hose into and through thetube, which itself can cause an increase in air supply pressure withoutthere actually being a lance stall. Hence a sufficient pressure changeto trigger reversal can occur without the lance actually encountering anobstacle. Further, the forward air pressure applied in a forwarddirection to the drive motor in typical industrial cleaning operationsgenerally varies widely and thus the conventional system is prone tospurious pneumatic pressure spikes and hence reversals are frequent.This is undesirable. What is needed therefore is an apparatus and methodfor reliably detecting a restriction within a heat exchanger tube orother piping system conduit being cleaned reliably and with precision.

SUMMARY OF THE DISCLOSURE

A flexible lance drive apparatus and an automatic blockage sensor inaccordance with the present disclosure directly addresses such needs.One exemplary embodiment of a flexible lance drive apparatus inaccordance with the present disclosure includes a generally rectangularhousing having an array of upper and lower drive rollers in an outersection each rotatably supported by an axle shaft passing laterallythrough spaced outer and inner walls defining a mid section of thehousing. A pneumatic drive motor is housed within the mid section of thehousing and is connected to each of the upper and lower drive rollers.Each lower drive roller shaft is rotatably supported in a fixed positionand the upper rollers may be lowered against the lower rollers via apneumatic cylinder to sandwich a flexible lance therebetween. This driveapparatus may be positioned adjacent an entrance into a piping system tobe cleaned, such as mounted on a frame fastened to a tube sheet of aheat exchanger tube bundle.

A control console is connected to the drive motor and to the pneumaticcylinder in the drive apparatus via forward and reverse pneumaticpressure supply lines such that an operator can stand at the controlconsole remotely from the drive apparatus so as to avoid the highpressure water spray from the apparatus during operation. The consolehas forward and reverse manual controls for directing pneumatic pressurevia the pneumatic lines to forward and reverse sides of the drive motor.In this embodiment a four way solenoid valve is connected across theforward and reverse pressure lines adjacent the control console. Thissolenoid valve is operable to reverse the pneumatic pressure connectionsto the drive motor when energized.

An automatic blockage sensing circuit, in one exemplary embodiment, ismounted within the control console or attached to it, remote from thelance drive apparatus. In other embodiments, the automatic blockagesensing circuit may be housed within the drive apparatus itself. Thiscircuit is operable to sense, at the pneumatic drive motor, a drivemotor pressure differential increase above a predetermined threshold andenergize the solenoid valve to reverse the pneumatic pressure lineconnections to the drive motor when this occurs. This function of theautomatic blockage sensing circuit and the four way solenoid valve areoperable only when the forward manual control at the control console issupplying pneumatic pressure to the drive motor.

The automatic blockage sensing circuit comprises a first pressuretransducer connected to a forward air port at the drive motor and asecond pressure transducer connected to a reverse air port at the drivemotor via sensing lines connected directly to the drive motor, and amicrocontroller configured to monitor a differential pressure betweenthe transducers, compare the differential pressure to a predeterminedthreshold and generate an electrical current output when the thresholdis exceeded.

The present disclosure also describes a method of automatically clearingan obstruction encountered while cleaning one or more tubes in a tubesheet of a heat exchanger with a flexible lance drive apparatus having alinear array of driven rollers propelling one or more flexible lancesinto the one or more tubes. This method includes sensing a pneumaticsupply pressure applied to a pneumatic lance drive motor at thepneumatic lance drive motor during forward operation; sensing apneumatic pressure at an opposite side of the drive motor during forwardoperation; determining a difference between the pressures; comparing thedifference to a predetermined difference threshold; and reversing thesupply line connections to the drive motor so as to reverse motordirection for a predetermined time interval if the difference exceedsthe threshold The process may include restoring the supply lineconnections after the predetermined time interval and repeating thesensing, reversing and restoring operations until the difference nolonger exceeds the predetermined difference threshold.

An exemplary embodiment in accordance with the present disclosure mayalternatively be viewed as a flexible high pressure fluid cleaning lancedrive apparatus that includes a housing, at least one drive motor havinga drive axle in the housing carrying a cylindrical spline drive roller,and a plurality of cylindrical guide rollers on fixed axles alignedparallel to the spline drive roller. A side surface of each guide rollerand the at least one spline drive roller is tangent to a common planebetween the rollers. An endless belt is wrapped around the at least onespline drive roller and the guide rollers. The belt has a transversesplined inner surface having splines shaped complementary to splines onthe spline drive roller.

The drive apparatus further has a bias member supporting a plurality offollower rollers each aligned above one of the at least one spline driveroller and guide rollers, wherein the bias member is operable to presseach follower roller toward one of the spline drive rollers and guiderollers to frictionally grip a flexible lance hose when sandwichedbetween the follower rollers and the endless belt. The apparatusincludes a first sensor coupled to the drive roller for sensing positionof the endless belt, a second sensor coupled to a first one of thefollower rollers for sensing position of the first follower rollerrelative to a first flexible lance hose sandwiched between the firstfollower roller and the endless belt, and at least a first comparatorcoupled to the first and second sensors operable to determine a firstmismatch between the first follower roller position and the endless beltposition.

The apparatus preferably further includes a third sensor coupled to asecond one of the follower rollers for sensing position of the secondone of the follower rollers relative to a second flexible lance hosesandwiched between the second one of the follower rollers and theendless belt. The exemplary apparatus also may include a secondcomparator operable to compare the second follower roller position tothe endless belt position and determine a second mismatch between thesecond follower roller position and the endless belt position.

Preferably a controller is coupled to the first comparator and thesecond comparator operable to initiate an autostroke sequence ofoperations upon the first mismatch and second mismatch differing by apredetermined threshold. A fourth sensor may be coupled to a third oneof the follower rollers for sensing position of the third one of thefollower rollers relative to a third flexible lance hose sandwichedbetween the third one of the follower rollers and the endless belt.Also, a third comparator may be provided operable to compare the thirdfollower roller position to the endless belt position and determine athird mismatch between the third follower roller position and theendless belt position. The controller is preferably coupled to the firstcomparator, the second comparator and the third comparator and isoperable to initiate an autostroke sequence of operations upon any oneof the first, second and third mismatches exceeding a predeterminedthreshold. Furthermore, the controller is preferably operable to modifyclamping pressure if more than one of the first, second and thirdmismatches exceed a different predetermined threshold. The sensors maybe magnetic or preferably Hall effect sensors.

A flexible high pressure fluid cleaning lance drive apparatus inaccordance with the present disclosure may comprise a housing, at leastone drive motor having a drive axle in the housing carrying acylindrical spline drive roller, a plurality of cylindrical guiderollers on fixed axles aligned parallel to the spline drive roller, andwherein a side surface of each guide roller and the at least one splinedrive roller is tangent to a common plane between the rollers, anendless belt wrapped around the at least one spline drive roller and theguide rollers, the belt having a transverse splined inner surface havingsplines shaped complementary to splines on the spline drive roller, abias member supporting a plurality of follower rollers each alignedabove one of the at least one spline drive roller and guide rollers,wherein the bias member is operable to press each follower roller towardone of the spline drive rollers and guide rollers to frictionally grip aflexible lance hose when sandwiched between the follower rollers and theendless belt.

The apparatus includes a first sensor coupled to the drive roller forsensing endless belt position and a plurality of second sensors eachcoupled to one of the plurality of follower rollers each for sensingposition of the one of the follower rollers relative to a flexible lancehose sandwiched between the one of the follower rollers and the endlessbelt. The apparatus preferably includes a first comparator coupled tothe first sensor and each second sensor operable to determine a mismatchbetween each follower roller position and the endless belt position. Theapparatus may further include a second comparator operable to compareeach of the plurality of flexible lance hose positions with each otherto determine another mismatch therebetween and a controller coupled tothe second comparator operable to initiate an autostroke sequence ofoperations upon the another mismatch exceeding a predeterminedthreshold.

An apparatus in accordance with the present disclosure may alternativelybe viewed as including a housing, at least one drive motor having adrive axle in the housing carrying a cylindrical drive roller, aplurality of cylindrical guide rollers on fixed axles aligned parallelto the drive roller, and wherein a side surface of each guide roller andthe at least one drive roller is tangent to a common plane between therollers, an endless belt wrapped around the at least one drive rollerand the guide rollers, a bias member supporting a plurality of followerrollers each aligned above one of the at least one drive roller andguide rollers, wherein the bias member is operable to press eachfollower roller toward one of the drive rollers and guide rollers tofrictionally grip a flexible lance hose when sandwiched between thefollower rollers and the endless belt, a first sensor coupled to thedrive roller for sensing endless belt position, a plurality of secondsensors each coupled to one of the plurality of follower rollers eachfor sensing position of the one of the follower rollers relative to aflexible lance hose sandwiched between the one of the follower rollersand the endless belt, a first comparator coupled to the first sensor andeach second sensor operable to determine a mismatch between eachfollower roller position and the endless belt position, and a secondcomparator coupled to each of the second sensors operable to determine amismatch between any two of the follower roller positions. The apparatusmay also preferably include a controller coupled to the secondcomparator operable to initiate an autostroke sequence of operationsupon the mismatch exceeding a predetermined threshold and may furtherinclude the controller being operable to initiate a change of clamppressure if the mismatch between the follower roller positions and thebelt position all or at least more than one, exceed a predeterminedthreshold.

Further features, advantages and characteristics of the embodiments ofthis disclosure will be apparent from reading the following detaileddescription when taken in conjunction with the drawing figures.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a flexible lance drive apparatus inaccordance with the present disclosure.

FIG. 2 is a diagram of the pneumatic connections between a remoteoperator's control console and the drive apparatus shown in FIG. 1.

FIG. 3 is a schematic electrical and pneumatic control diagram of theapparatus shown in FIG. 2.

FIG. 4 is a side perspective view of another flexible lance driveapparatus incorporating an embodiment of an autostroke functionality inaccordance with the present disclosure, shown with its outer side doorremoved.

FIG. 5 is a side perspective view of the drive apparatus shown in FIG. 4with upper and lower side plates removed to show the belt drivestructure.

FIG. 6 is an opposite side view of the drive apparatus shown in FIG. 4,again with an outer side door removed for clarity.

FIG. 7 is a partial vertical sectional view through belt and lanceportion of the drive apparatus shown in FIG. 4 taken on the line 7-7.

FIG. 8 is a separate side view of one of the belt drive motors with itsouter cover shown transparent to reveal an internal annular disc shapedtarget fastened to the rotor of the motor.

FIG. 9 is a simplified block diagram of the signal processing circuitryin the apparatus shown in FIGS. 4-8.

FIG. 10 is a process flow diagram for the Autostroke functionality forthe embodiment shown in FIGS. 4-8.

FIG. 11 is a process flow diagram for the Autostroke subroutine inaccordance with the present disclosure.

FIG. 12 is a process flow diagram for the automated clamp pressurecontrol in accordance with the present disclosure.

DETAILED DESCRIPTION

An exemplary drive apparatus 100 incorporating an automatic blockagesensor in accordance with the present disclosure is shown in FIG. 1 witha side cover open showing the set of 3 pairs of drive rollers 102arranged for driving two flexible lances 104 in accordance with oneembodiment of the present disclosure. The apparatus 100 includes ahousing 106 in which a drive motor 108 drives each of the six driverollers 102. FIG. 1 shows a drive apparatus 100 supported for guidingone or more flexible lance hoses 104 into and out of a tube in a tubesheet 110. The drive apparatus 100 is typically mounted on a flexiblelance guide 117 which is fastened to a frame 119 that places the driveapparatus 100 in alignment with the tubes penetrating the tube sheet110.

The drive apparatus 100 is pneumatically remotely controlled via acontrol console 200, as shown in FIG. 2, carried by or positionedadjacent to an operator (not shown) standing a safe distance from theapparatus 100. Attached to the control console 200 is an automaticblockage sensing control circuit box 220. This automatic blockagesensing control circuit box 220 houses an electronic monitoring circuitthat monitors air motor pressure at the air motor 108 in the driveapparatus 100 shown in FIG. 1 and controls a solenoid valve also locatedin or adjacent to the box 220 as will be described more fully below.

The operator preferably can stand about 20-40 feet from the driveapparatus 100. The operator pneumatic control console 200, shown in FIG.2, in accordance with the present disclosure connects to an air pressuresupply source line (not shown) and includes a forward line 202 connectedto the air motor 108 in the drive apparatus 100, a retract, or reverse,line 204 connected to the air motor 108, and a clamp air line (notshown) that connects to an air cylinder in the housing 106 in theapparatus 100 for adjusting clamp pressure of the row of upper rollers102 on the lance(s) 104.

A pair of pressure sensing lines 208 and 210 is connected directly tothe forward and reverse ports on the motor 108 in the apparatus 100.These sensing lines 208 and 210 connect to a pair of pressuretransducers 212 and 214 mounted in the control box 220 shown in theschematic diagram shown in FIG. 3. Each pressure transducer 212 and 214produces an electrical signal, either current or voltage, proportionalto the pressure sensed at its particular side of the air motor 108.

The automatic blockage sensing control box 220 includes amicrocontroller 222 that utilizes the forward pressure signal fromtransducer 212 to determine when to institute an autostroke cycle orevent. More precisely, the microcontroller 222 utilizes the signals fromboth transducer 212 and 214 to compute a pressure differential. When thepressure differential exceeds a threshold value the autostroke event istriggered. When the pressure difference between the applied air pressurein the forward direction through line 202 sensed at the air motor 108and the pressure sensed at the reverse port at the air motor 108increases to a predetermined value indicative of high torque caused bythe nozzles encountering a restriction or blockage in the tube(s) beingcleaned, the microcontroller 222 produces an output on lines A1-A2 whichcloses a switch 224 to apply 12 volts DC to a solenoid valve 226 throughwhich the forward and reverse lines 202 and 204 are connected. Thisswitch 224 is preferably a solid state transistor switch. When thesolenoid valve 226 is energized, the ports within the valve 226 redirectthe forward air motor pressure to the opposite (reverse) side of the airmotor 108. After a predetermined period of motor reversal, the solenoidvalve 226 is de-energized and the forward air pressure restored to theforward port of the motor 108, at which time forward lance movementresumes if the operator is still pressing the forward control button. Ifthe obstruction is again met, motor pressure again increases as themotor bogs down, and the process repeats.

The automatic blockage sensor control box 220 has two potentiometers 228and 230. Potentiometer 228 is used to adjust the threshold pressuredifferential at which the microcontroller 222 will close the switch 224to energize the solenoid 226, and thereby direct forward drive pneumaticpressure to the reverse port of the air motor 108. The potentiometer 230is used to adjust the length of time that pneumatic pressure is divertedto the reverse direction of air motor 108, and hence the lanceretraction distance before air pressure is restored to the forwarddirection of the air motor 108.

The microcontroller 222 continually monitors and compares this thresholdto the sensed forward pressure via transducer 212. If the pressuredifference rises above the threshold, an autostroke event is triggered.When this occurs while the operator is holding the “Hose Feed” controlin the forward direction, the microcontroller 222 actuates the solenoidvalve 226 which reverses the pneumatic pressure connection from theforward feed line 202 to the reverse line 204. This solenoid valve 226is a 5-way two position valve that is internally piloted. The forwardair hose 202 is connected to the pressure port of the valve 226 and thereverse air hose 204 is tee'd to both of the exhaust ports on the valvewhich effectively makes valve 226 a 4 way valve. Because the solenoidvalve 226 is internally piloted, it will only shift when the operator isdriving the drive apparatus 100 forward.

FIG. 3 is a composite schematic of the pneumatic system between theseparate control console 200 and the drive apparatus 100, andincorporates, in the dashed portion, the electronic circuitry within theautomatic blockage sensor control box 220. The solenoid valve 226 may bemounted within the control box 220 or it may be mounted separatelybetween the control box 220 and the drive apparatus 100. Alternativelythe control box 220 and the solenoid valve 226 could be integratedcompletely into the housing of the drive apparatus 200.

In FIG. 3, the power source 232 is shown as being 12 volts DC. Othersupply voltages may be utilized depending on the requirements of themicrocontroller 222 and the solenoid valve 226. Furthermore, the powersource 232 may be a battery, a series of batteries, or, for example, apneumatic/electric generator appropriately selected according to thepower requirements of the solenoid valve 226 and the microcontroller222. An on-off switch 234 is also provided in series with the powersource 232 to remove the autostroke functionality when not desired.

Another embodiment of a multiple lance drive apparatus 300 incorporatingan autostroke functionality for each lance driven by the drive apparatus300 is shown in FIGS. 4-9. Referring now to FIG. 4, a belt side view ofthe apparatus 300 is shown with its side cover removed. The driveapparatus 300 has a rectangular box housing 302 that includes a flat topplate 304, a bottom plate 306, front and rear walls 308 and 310, and twoC shaped carry handles 312, one on each of the front and rear walls 308and 310. In FIGS. 4-10, sheet side covers (not shown) are removed sothat internal components of the apparatus 300 are visible.

Fastened to the front wall 308 is an exit hose guide manifold 314.Fastened to the rear wall 310 below the carry handle 312 is a hoseentrance guide manifold 316. Each of these manifolds 314 and 316includes a set of hose guide collets 318 for guiding one to threeflexible lance hoses (not shown) into and out of the housing 302. Eachguide collet set 318 is sized to accommodate a particular lance hosediameter. Hence the collet sets are changeable depending on the lancesize to be driven by the apparatus 300. Each of the manifolds 314 and316 includes a sensor, typically a hall effect sensor (not shown) fordetecting presence or absence of a metal hose stop element that isfastened to each flexible lance hose. These sensors are used to stop theapparatus 300 when presence of a hose stop element is sensed. One hosestop element is preferably integrated into the threaded hose ferrule towhich a nozzle is attached, at the end of each of the lance hoses. Thisparticular hose stop element is configured to prevent inadvertentwithdrawal of the flexible lance out of the heat exchanger tube sheetand into the drive apparatus 300. The forward manifold 314 may alsoinclude a physical collet assembly to mechanically prevent flexiblelance nozzle withdrawal into the drive apparatus 300. Another hose stopelement is removably fastened to each of the lance hoses short of therear manifold 316 to prevent over insertion of a flexible lance beyondthe tube being cleaned. These removable hose stop elements may pairs ofC shaped metal clamps that are fastened to the hose at a predeterminedhose length from the nozzle end to indicate full insertion of theflexible lance through a target tube sheet and tube being cleaned.

A motor side view of the apparatus 300 is shown in FIG. 6 with its outerside cover removed. The housing 302 includes an inner vertical supportpartition wall 320 fastened to the front and rear walls 308 and 310 andthe top and bottom plates 304 and 306. This vertical support partitionwall 320 divides the housing into a first portion and a second portion.The first portion primarily houses hose fittings and splined belt drivemotors 322 and 324. The second portion is a belt cavity 321 throughwhich flexible lance hoses (not shown) are driven, and is shown at leastin FIGS. 4, 5 and 6.

In this exemplary embodiment 300, the inner vertical support wall 320carries a pair of pneumatic drive motors 322 and 324 mounted such thattheir drive shafts 326 and 328 protrude laterally through the supportwall 320 into the second portion, or belt cavity 321, between the innervertical wall 320 and an outer vertical lower support wall 330, shown inFIGS. 4 and 5. Each of the drive motors 322 and 324 is connected topneumatic forward feed line 332 and reverse feed line 334 through a feedmanifold 336 fastened to the top plate 304. A clamp pressure feed linefitting 338 also passes through this feed manifold 336 to a hose clampassembly 344 described below. Each of the drive motors 322 and 324,shown in FIG. 6, is preferably a compact radial piston pneumatic motor.However, hydraulic or electric motors could alternatively be used.

On the belt side view shown in FIGS. 4 and 5, the belt cavity 321 isdefined between the inner vertical wall 320 and the outer lower supportwall 330. A separate upper outer support wall 340 aligned with the lowerouter support wall 330 provides a rigid joint between the front and rearwalls 308 and 310 while providing a visible space between the entranceand exit guide manifolds 316 and 314. This spacing helps an operatorthread up to three lances laterally into and through the belt cavity 321between an endless drive belt 342 and a vertically arranged hose clampassembly 344. Each of the support walls 320, 330 and 340 is preferable aflat plate of a lightweight material such as aluminum or could be madeof a structural polymer with sufficient strength and rigidity to handlethe motor operational stresses involved.

The upper outer support wall 340 carries a set of electrical connectors343 for communication of sensed hose position, hose stop presence andbelt position via the drive motor direction and position sensorsdescribed below, and a set of 14 LED lights 345 to indicate the statusof each of these elements during drive apparatus operation.

A perspective view of the apparatus 300 with the upper and lower outervertical support walls 340 and 330 removed is shown in FIG. 5. Each ofthe motor drive shafts 326 and 328 has an axial keyway fitted with acomplementary key (not shown) that engages a corresponding keyway in acylindrical splined drive roller 346. Thus each drive roller 346 isslipped onto and keyed to the drive shaft so as to rotate with the driveshaft 326 or 328. Each splined drive roller 346 has its outercylindrical surface covered with equally spaced splines extendingparallel to a central axis of the roller 346. The distal ends of each ofthe drive shafts 326 and 328 extends through the lower outer supportwall 330 and are primarily laterally supported from plate 320.Additional lateral support for the distal ends of each of the driveshafts 326 and 328 is provided by the lower outer support wall 330 viacone point set screws engaging a V groove (not shown) in each of theshafts 326 and 328.

Each of the drive shafts 326 and 328 may extend fully through thesplined drive rollers 346 or the drive motors 322 and 324 may each befitted with a stub drive shaft which fits into a bearing within theproximal end of each of the splined drive rollers 346. A separatebearing supported drive shaft 326 or 328 extends out of the distal endof each drive roller 346 and is fastened to the support wall 330 viacone point set screws. In such an alternative, the drive rollers 346become part of the drive shafts 326 and 328.

Spaced between the two splined drive rollers 346 is a set of fourcylindrical guide rollers 348 that are supported by the lower outersupport wall 330 via a vertical plate 350 and a pair of rectangularvertical spacer blocks 352 that are through bolted to both the lowerouter support wall 330 and inner vertical wall 320 through the verticalplate 350 via bolts 354. While the bolts 354 pass through the verticalplate 350, their distal ends extend further through, and are threadedinto holes through the inner vertical wall 320.

Tension on the endless belt 342 is preferably provided by a tensionerroller 358 between the spacer blocks 352 that is supported from theinner vertical plate 350 on an eccentric shaft 360, and accessed throughan opening 362 in the inner vertical wall 320, shown in FIG. 6. Rotationof this eccentric shaft 360 essentially moves the tensioner roller 358through a slight arc downward or upward to provide more or less tensionon the belt 342.

To replace the belt 342, the four bolts 354 are loosened and screwsholding the outer lower wall 330 to the front and rear walls 308 and 310are removed. The cone point set screws engaging a V groove (not shown)in each of the shafts 326 and 328 are then removed. The assembledstructure including the vertical plate 350, spacer blocks 352, belt 342,drive rollers 346, and guide rollers 348 can then be removed as a unitby sliding the drive rollers 346 off of the keyed shafts 326 and 328.

Each of the splined drive rollers 346 preferably has equally spacedalternating spline ridges and grooves around its outer surface which arerounded at transition corners so as to facilitate engagement of thecomplementary shaped lateral spline ridges and grooves in the inner sideor surface of the endless belt 342. Elimination of sharp transitions atboth ridge corners and groove corners lengthens belt life while ensuringproper grip between the rollers and the belt. The outer surface portionor cover of the endless belt 342 is preferably flat and smooth toprevent undesirable hose abrasion and degradation and is preferablyformed of a suitable friction material such as polyurethane. The innerside portion of the belt 342 is preferably a harder durometerpolyurethane material bonded to the outer side cover. For applicationswith significant hydrocarbons or high lubricity products, groovesmachined across the cover at 90° to the direction of belt travel may beutilized for improved traction performance against the flexible lancehose.

Spaced above the belt 342 in the belt cavity is a lance hose clampassembly 344 including an idler roller assembly 370. This exemplaryclamp assembly 344 includes a multi-cylinder frame 372 fastened to thetop plate 304 of the housing 302. The multi-cylinder frame 372 carriestwo or three single acting pneumatic cylinders with pistons 374 (shownin FIG. 7) that are each connected to a carrier block 376 and connectedtogether via a pair of parallel spaced idler carrier frame rails 378.Six idler roller sets 380 are carried by the frame rails 378, eachvertically positioned directly above either one of the drive rollers 346or one of the guide rollers 348. Each piston 374 may be spring biasedsuch that without pneumatic pressure, the pistons 374 are all withdrawnor retracted fully into the multi-cylinder frame 372 so as to provideaccess space between the idler roller sets 380 and the drive belt 342for insertion and removal of flexible lance hoses.

One set of idler rollers 380 is made up of three independent spoolshaped bearing supported rollers 382 shown in the sectional view throughthe apparatus 300 shown in FIG. 7. This particular set 380 of idlerrollers 382 is positioned adjacent hall effect sensors 400, 402, and404, mounted on a circuit board 385 fastened to the underside of thecarrier block 376, to detect distance traveled by each hose being driventhrough the drive apparatus 300. Each roller 382 is a spool shapedroller having a central concave, or U shaped, groove bounded by oppositecircular rims 383. One of the rims 383 of each roller 382, preferably aninboard rim 383, carries a series of 24 magnets embedded around the rim383, each having an opposite polarity in series facing radially outward.

The printed circuit board 385 fastened to the underside surface of theupper support block 376 carries 3 hall effect sensors 400, 402, and 404each arranged adjacent one of the rims 383. As each roller 382 rotates,for example, by 15 degrees, one of the magnets passes beneath itsadjacent sensor 400, 402, or 404 on the pcb 385 and a polarity change isdetected. These changes are counted and converted to precise relativelance distance traveled for that particular lance (not shown). In thisway, very precise distance traveled by the lance can be determinedirrespective of the distance traveled by an adjacent lance driven by thedrive apparatus 300.

Each idler roller set 380 is carried on a stationary axle 390 fastenedbetween the idler frame rails 378. Only one idler roller set 380 needsto have separate rollers 382. The other 5 idler roller sets 380 eachpreferably is a bearing supported cylindrical body having three axiallyspaced annular spool shaped concave grooves each being complementary tothe anticipated lance hose size range. These annular grooves may be Vshaped, semicircular, partial trapezoidal, rectangular, or smooth Ushaped so as to provide a guide through the apparatus 300 and keep theflexible lances each in desired contact with the endless belt 342 duringtransit. Preferably the idler rollers 380 and the individual rollers 382are made of aluminum or other lightweight material capable ofwithstanding bending loads and each groove has a concave arcuatecross-sectional shape. Each groove may alternatively be a wide almostrectangular slot with corners having a radius profile to allow the hosesto have limited lateral movement as they are fed through the apparatus300. This latter configuration is preferred in order to accommodateseveral different lance hose diameters in the drive apparatus 300.

In use, the drive apparatus 300 may be utilized with one, two, or threeflexible lances simultaneously. In the case of driving one lance, such alance would be preferably fed through the center passage through theinlet manifold 316 and beneath the center groove of the idler rollers380. When two lances are to be driven, the inner and outer passagesthrough collets 318 would be used. If three lances are to be driven, onewould be fed through each collet 318 and corresponding groove of eachidler roller 380.

In alternative embodiments, more than three lance drive paths may beprovided such as 2, 4 or five. Electrical or hydraulic actuators andmotors may be used in place of the pneumatic motors shown and described.Although a toothed or spline endless belt is preferred as described andshown above, alternatively a smooth belt or grooved belt with widerspline spacing could be substituted along with appropriately configureddrive rollers. The guide rollers 348 are shown as being smoothcylindrical rollers. They may alternatively be splined rollers similarto the drive rollers 346.

One of the splined belt drive motors, motor 322 in the illustratedembodiment 300, is configured with a differential hall effect sensor 389to monitor speed and direction of rotation of the drive motor 322, andhence lance travel along the belt 342 through the drive apparatus 300. Aseparate plan view of drive motor 322 is shown in FIG. 8, with its outercover shown transparent. An annular notched target disc 391 is fastenedto the motor rotor inside the motor housing 393, having spaced notchesforming 18 teeth 395. The differential hall sensor 389 fastened to thehousing 393 senses passage of each of these teeth 395 and outputs avoltage change signal for each transition. The signal output isindicative of direction of rotation and speed, which mathematicallyequates to belt position and hence lance travel distance, assuming noslip between belt and lance hose.

By comparing the position of the lance hoses, i.e. distance traveled assensed from the follower roller set sensors 400, 402, and 404, for eachof the lance hoses, with the belt drive motor speed and direction senseddistance from the signal output of sensor 389, any mismatch iscorrelated to lance to belt slippage. For example, when driving threelances, if a large mismatch on only one lance occurs, in a three lancedrive operation, this is typical of a blockage or restriction in thatparticular tube being cleaned.

If all the lances, 3 in the illustrated case, have a similar mismatchwith respect to the belt drive motor sensed position and/or feeddistance, this will be indicative of insufficient clamp pressure. Inthis instance the operator can simply increase clamp pressure tocompensate for the mismatch. The operator can then re-zero the lanceposition and look for subsequent mismatch. Alternatively an automaticcontrol system can perform this function, as is described in more detailbelow. In such a case the clamp pressure may be automatically increasedto minimize slippage, up to a predetermined maximum applied pressureapplied to the follower rollers 380.

In the event of a single lance hose mismatch, as first described above,this indicates a restriction, or blockage, occurring in the tube beingcleaned. The sensed mismatch preferably is used to trigger an autostrokesequence of motor 322 instigating reversals as generally describedabove, to move the lance hoses back and forth in the tubes beingcleaned, until the blockage or restriction is reduced or eliminated, asdetermined by re-zeroing the position of the mismatched lances andcontinuing the cleaning operation as needed, until another mismatchabove an operator determined threshold occurs.

The drive apparatus 300 may include the comparator circuitry to comparethe signals from each of the sensors 400, 402, and 404 with the signalfrom the drive motor sensor 389. The drive apparatus 300 may alsoinclude a comparator that compares the signals between each of thesensors 400, 402 and 404, as the lance position of each lance should berelatively close to each other since the only drive force is from thecontact with the drive belt 342. Alternatively the comparator circuitrymay be handled via microprocessor in a system controller separate fromthe apparatus 300. In either case, an exemplary signal processingcircuit is shown, in simplified block diagram form in FIGS. 9 andprocess flow diagrams FIGS. 10, 11 and 12.

A simplified functional block diagram 450 for autostroke control for theapparatus 300 is shown in FIG. 9. Motor sensor 389 feeds an input intothree comparators 460 each of which in turn send an input to controller500. At the same time, the sensors 400, 402 and 404 also send signals tothe comparators 460. The controller 500 serves two major functions:autostroke to remove tube blockages, and clamp pressure control. Theautostroke functionality is described below with reference to FIGS. 10and 11. The clamp pressure may be adjusted manually or may be controlledautomatically as described in FIG. 12.

Operational control of the apparatus 300, basically called a tractor,begins in operation 900, when a feed forward operation is selected bythe operator on a cleaning system controller (not shown). Thiscontroller may be floor mounted or may be a hand held controller thatcommunicates either wired or wirelessly with the apparatus 300. Oncefeed forward operation is selected, control transfers to tractor forwardoperation 902 which queries in operation 904 whether the Drive buttonhas been pressed. If the answer is yes, control transfers to comparatoroperation 906. If however, in query operation 904, the Drive button hasnot been pressed, control immediately transfers to stop operation 911where tractor forward operation is stopped.

Assuming the Drive button has been pressed, forward operation 902energizes the drive motors 322 and 324 causing the endless belt 342 topull 1, 2 or 3 lances along the pathway between inlet manifold 314 andoutlet manifold 316 through the apparatus 300. As the lances move alongthe endless belt 342, their movement causes the follower rollers 382 torotate, sending signals, picked up by sensors 400, 402 and 404, tocomparators 460. At the same time, sensor 389 on motor 322 sends asimilar signal to each of the comparators 460.

Operation 906 receives linear lance position information from sensors400, 402, and 404 via the circuit board 385 for each lance. Comparatoroperation 906 also receives belt position information from the sensor389 on the drive motor 322. In operation 906, the received signals areconverted to actual lance feed distances and the expected feed distanceis compared to the actual feed distance of each lance.

Control then transfers to query operation 908 where the question isasked whether expected feed to actual feed of each lance differs overtime. In other words, whether there is a mismatch between expected feeddistance and actual distance fed. If below a user settable difference,the answer is NO, a “continue drive” control signal is sent back tooperation 902 and the tractor continues to drive the lances forward. Onthe other hand, if there is a substantial difference in expected toactual feed for any one of each individual lance, then the answer isYES, and control transfers to Autostroke subroutine operation 910, shownin detail in FIG. 10. On the other hand, if there is a substantialdifference in expected to actual feed, i.e. a mismatch, for more thanone individual lance detected in operation 908, this is indicative ofinsufficient clamp pressure, and the controller 500 transfers control toclamp pressure operational sequence 950 described in FIG. 12.

An autostroke routine begins in operation 912. Control then transfers toreset operation 914 where the lance to motor difference for each lanceis set to zero and an incrementing counter is set to zero. Control thentransfers to operation 916 where the increment counter is advanced by 1.Control then transfers to operation 918 where drive apparatus 300 issignaled to drive backward for N increments. Control then transfers tooperation 920, where the drive apparatus 300 is signaled to driveforward N+1 increments. Control then transfers to query operation 922.

Query operation 922 asks whether the counter value is greater than orequal to 10, or a predetermined number other than 10. If the answer isno, control transfers back to operation 916 where the counter isincremented again and the process operations 918, 920 and 922 arerepeated. If the answer in query operation 922 is yes, the counter isgreater than or equal to 10, control transfers to query operation 924which asks whether a mismatch between lance position and motor positioncounts still exists. If the answer is yes, a mismatch is still present,this indicates that there is still a blockage or restriction in thetarget tube or tubes. Control transfers to operation 926.

In query operation 926, the question is asked whether the apparatus 300feed rate is at a minimum. If the answer is yes, control transfers tostop operation 928. This indicates that an unremovable obstruction hasbeen encountered, requiring manual operator action to mark the tube asblocked or take other appropriate action. In query operation 926, if theanswer is no, feed rate is not yet at minimum, control transfers tooperation 930.

In operation 930, the tractor feed rate of apparatus 300 is reduced.Control then transfers back to operation 914 where the lance to driveposition mismatch is set to zero and the incrementing counter are set tozero, and the iterative process of operations 916 through 924 isrepeated.

On the other hand, if in query operation 924, there is no mismatchpresent, this means that either no obstacle is now sensed, i.e. theobstacle has been cleared, and control returns to operation 902, wherenormal tractor drive forward operation is resumed, until the drivebutton in operation 904 is released, which stops tractor forward feed inoperation 911.

A process flow diagram 950 of the controller 500 is shown in FIG. 12 foradjusting the clamp pressure of pistons 374 to press follower rollers380 against a set of one or more hoses (not shown) being driven alongthe endless belt 342 Basically, if there is a mismatch as determined bycomparators 460 for more than one lance hose, this is potentiallyindicative of insufficient clamp pressure. The process begins inoperation 952. The controller 500 senses if a lance hose registers amismatch in operation 952. Control then transfers to query operation954, which asks if there is more than one lance comparator signaling amismatch. If so, control transfers to query operation 956. If not,control transfers back to operation 902 described above.

In query operation 956, the query is made whether clamp pressure is ator above a predetermined maximum pressure. If the answer is yes, controltransfers to operation 960 where a flag is sent and clamp pressurecontrol is transferred to manual for the operator to assess and takeappropriate action. If the answer in query operation 956 is no, pressureis not at maximum, control transfers to operation 958, where clamppressure is increased by a predetermined amount, such as 2 psi. Controlthen transfers back to query operation 954 and operations 954, through956 are repeated until the mismatch determined in operation 954 is lessthan or equal to 1. Control then transfers back to operation 902described above.

Many variations are envisioned as within the scope of the presentdisclosure. For example, all components of the control box 220 may bephysically housed within the control console 200. Alternatively, thecomponents within the control box 220 could be integrated into the driveapparatus 100 or into the drive apparatus 300. In the case of Driveapparatus 300, the control circuitry may be housed in a separate handheld controller as described in concurrently filed patent applicationAttorney Docket Number 122853.019801, the content of which isincorporated herein by reference in its entirety. The number of drivereversals in the Autostroke sequence is predetermined, but it may be anynumber. A value of >=10 was chosen as merely exemplary. In alternativeembodiments, electrical or hydraulic actuators and motors may be used inplace of the pneumatic motors shown and described herein.

Furthermore, the follower roller need not be one of the follower rollers382 shown in FIG. 5. The follower rollers that operate with the sensors400, 402, 404 may be a separate spring loaded structure that presses onthe flexible lance hose or hoses. The sensors may be other than Halleffect sensors specifically mentioned above. For example, gear toothsensors may be used. Hall effect sensors described above are merelyexemplary of one embodiment. Different automated routines andsubroutines than as described above may be utilized to control theoperation of the apparatus 300. In addition, the apparatus 300 may beconfigured with status lights to indicate mismatches between lances andthe drive motor, lance relative position, as well as such things as feedrate and other indications of proper operation. These may include lancewithdrawal stop indicators and lance insertion stop indicatorspositioned on the inlet and outlet manifolds 314 and 316. Therefore, allsuch changes, alternatives and equivalents in accordance with thefeatures and benefits described herein, are within the scope of thepresent disclosure. Such changes and alternatives may be introducedwithout departing from the spirit and broad scope of this disclosure asdefined by the claims below and their equivalents.

What is claimed is:
 1. A flexible high pressure fluid cleaning lancedrive apparatus comprising: a housing; at least one drive motor having adrive axle in the housing carrying a cylindrical spline drive roller; aplurality of cylindrical guide rollers on fixed axles aligned parallelto the spline drive roller, and wherein a side surface of each guideroller and the at least one spline drive roller is tangent to a commonplane between the rollers; an endless belt wrapped around the at leastone spline drive roller and the guide rollers, the belt having atransverse splined inner surface having splines shaped complementary tosplines on the spline drive roller; a bias member supporting a pluralityof follower rollers each aligned above one of the at least one splinedrive roller and guide rollers, wherein the bias member is operable topress each follower roller toward one of the spline drive rollers andguide rollers to frictionally grip a flexible lance hose when sandwichedbetween the follower rollers and the endless belt; a first sensorcoupled to the drive roller for sensing position of the endless belt; asecond sensor coupled to a first one of the follower rollers for sensingposition of the first follower roller relative to a first flexible lancehose sandwiched between the first follower roller and the endless belt;and a first comparator coupled to the first and second sensors operableto determine a first mismatch between the first follower roller positionand the endless belt position.
 2. The apparatus according to claim 1further comprising a third sensor coupled to a second one of thefollower rollers for sensing position of the second one of the followerrollers relative to a second flexible lance hose sandwiched between thesecond one of the follower rollers and the endless belt.
 3. Theapparatus according to claim 2 further comprising a second comparatoroperable to compare the second follower roller position to the endlessbelt position and determine a second mismatch between the secondfollower roller position and the endless belt position.
 4. The apparatusaccording to claim 3 further comprising a controller coupled to thefirst comparator and the second comparator operable to initiate anautostroke sequence of operations upon the first mismatch and secondmismatch differing by a predetermined threshold.
 5. The apparatusaccording to claim 2 further comprising a fourth sensor coupled to athird one of the follower rollers for sensing position of the third oneof the follower rollers relative to a third flexible lance hosesandwiched between the third one of the follower rollers and the endlessbelt.
 6. The apparatus according to claim 5 further comprising a thirdcomparator operable to compare the third follower roller position to theendless belt position and determine a third mismatch between the thirdfollower roller position and the endless belt position.
 7. The apparatusaccording to claim 6 further comprising a controller coupled to thefirst comparator, the second comparator and the third comparatoroperable to initiate an autostroke sequence of operations upon any oneof the first, second and third mismatches exceeding a predeterminedthreshold.
 8. The apparatus according to claim 7 wherein the controlleris operable to modify clamping force if the first, second and thirdmismatches exceed a different predetermined threshold.
 9. The apparatusaccording to claim 1 wherein the sensors are Hall effect sensors
 10. Theapparatus according to claim 5 wherein the first, second, third andfourth sensors are Hall effect sensors.
 11. A flexible high pressurefluid cleaning lance drive apparatus comprising: a housing; at least onedrive motor having a drive axle in the housing carrying a cylindricalspline drive roller; a plurality of cylindrical guide rollers on fixedaxles aligned parallel to the spline drive roller, and wherein a sidesurface of each guide roller and the at least one spline drive roller istangent to a common plane between the rollers; an endless belt wrappedaround the at least one spline drive roller and the guide rollers, thebelt having a transverse splined inner surface having splines shapedcomplementary to splines on the spline drive roller; a bias membersupporting a plurality of follower rollers each aligned above one of theat least one spline drive roller and guide rollers, wherein the biasmember is operable to press each follower roller toward one of thespline drive rollers and guide rollers to frictionally grip a flexiblelance hose when sandwiched between the follower rollers and the endlessbelt; a first sensor coupled to the drive roller for sensing endlessbelt position; a plurality of second sensors each coupled to one of theplurality of follower rollers each for sensing position of the one ofthe follower rollers relative to a flexible lance hose sandwichedbetween the one of the follower rollers and the endless belt; and afirst comparator coupled to the first sensor and each second sensoroperable to determine a mismatch between each follower roller positionand the endless belt position.
 12. The apparatus according to claim 11further comprising a second comparator operable to compare each of theplurality of flexible lance hose positions with each other to determineanother mismatch therebetween.
 13. The apparatus according to claim 12further comprising a controller coupled to the second comparatoroperable to initiate an autostroke sequence of operations upon theanother mismatch exceeding a predetermined threshold.
 14. The apparatusaccording to claim 11 further comprising a controller coupled to thesecond comparator operable to initiate a change of clamp force if themismatch between the follower roller positions and the belt position allexceeding a predetermined threshold.
 15. A flexible high pressure fluidcleaning lance drive apparatus comprising: a housing; at least one drivemotor having a drive axle in the housing carrying a cylindrical driveroller; a plurality of cylindrical guide rollers on fixed axles alignedparallel to the drive roller, and wherein a side surface of each guideroller and the at least one drive roller is tangent to a common planebetween the rollers; an endless belt wrapped around the at least onedrive roller and the guide rollers; a bias member supporting a pluralityof follower rollers each aligned above one of the at least one driveroller and guide rollers, wherein the bias member is operable to presseach follower roller toward one of the drive rollers and guide rollersto frictionally grip a flexible lance hose when sandwiched between thefollower rollers and the endless belt; a first sensor coupled to thedrive roller for sensing endless belt position; a plurality of secondsensors each coupled to one of the plurality of follower rollers eachfor sensing position of the one of the follower rollers relative to aflexible lance hose sandwiched between the one of the follower rollersand the endless belt; a first comparator coupled to the first sensor andeach second sensor operable to determine a mismatch between eachfollower roller position and the endless belt position; and a secondcomparator coupled to each of the second sensors operable to determine amismatch between any two of the follower roller positions.
 16. Theapparatus according to claim 15 wherein each of the sensors is a Halleffect sensor.
 17. The apparatus according to claim 15 furthercomprising a controller coupled to the second comparator operable toinitiate an autostroke sequence of operations upon the mismatchexceeding a predetermined threshold.
 18. The apparatus according toclaim 15 further comprising a controller coupled to the secondcomparator operable to initiate a change of clamp force if the mismatchbetween the follower roller positions and the belt position all exceed apredetermined threshold.
 19. The apparatus according to claim 15 whereinthe sensors are Hall effect sensors.
 20. The apparatus according toclaim 15 wherein drive motor has a flat annular toothed disc fastened tothe motor rotor within the motor housing and the sensor is a Hall effectsensor fastened to the motor housing.